Cameron Maybin (right) is welcomed to the plate by pitcher Clayton Richard after scoring on a hit by Logan Forsythe in the fifth inning against the Reds on Saturday night. Earnie Grafton • U-T

Chris Heisey hit a two-run homer off Clayton Richard in the seventh inning Saturday night to break a 3-3 tie and lead the Cincinnati Reds to a 6-5 victory over the Padres before 34,222 at Petco Park.

The homer was the fifth hit by the Reds over the last two nights and the second off Richard on Saturday night. Richard has given up 16 homers in 17 starts, tied for the sixth-most in the National League.

The teams exchanged first-inning homers. After the Reds took a 3-1 lead in the top of the fifth, the Padres again tied the game with single runs in the fifth and sixth.

But after third baseman Todd Frazier opened the seventh inning with a single to left, Heisey hit his third homer of the season over the entrance gate to the Padres bullpen in center.

However, the key run was the one the Reds scored after Heisey’s homer. Singles by catcher Devin Mesoraco (off Richard) and rookie shortstop Zack Cowart (off reliever Dale Thayer) resulted in the Reds’ final run when the Padres were unable to turn a double play on a Drew Stubbs grounder to short.

The Padres scored single runs in the seventh and eighth and had the bases loaded in the eighth when Chris Denorfia lined out to end the inning.

The Padres had six hits in the two innings, including run-scoring singles by Alexi Amarista and Logan Forsythe, who had the first three-hit game of his career. But they also stranded five runners in the two innings, including three in scoring position.

“We were one hit away and couldn’t get the extra hit,” said Black. “We played hard, we fought back. We were right there and couldn’t get that hit to push us over the top.”

Reds’ All-Star reliever Aroldis Chapman, who struck out Amarista, Chase Headley and Carlos Quentin on triple-digit fastballs, retired the Padres in order in the ninth to pick up his 10th save.

“It’s real velocity,” Black said of Chapman, who has a 1.88 ERA this season with 69 strikeouts in 38 1/3 innings after striking out the only three Padres he’s faced.

“When you are throwing 100 (mph) with deception and a late release, it’s hard to pick the ball up. It’s tough.”

The loss was the Padres’ second straight following a season-best, six-game winning streak. And eight of the Reds’ 12 runs over the past two nights came via the homer.

Cozart opened Friday’s game with a homer and catcher Ryan Hanigan and Frazier later added two-run homers in the Reds’ 6-0 win. On Saturday, Stubbs homered off Richard with one out in the first.

Denorfia immediately pulled the Padres even by sending Homer Bailey’s first pitch of the game 419 feet into the seats in right-center. The homer was Denorfia’s third of the season and the third game-opening homer of his career, as well as the Padres’ third this season.